Foodborne bacterial stress responses to exogenous reactive oxygen species (ROS) induced by cold plasma treatments

Cold plasma (CP) as an innovative and efficient technology has been developed for food sterilization. During CP treatments, exogenous reactive oxygen species (ROS) are generated, which are usually considered as the key bactericidal agent. Therefore, understanding various resistant mechanisms developed during CP processing by bacteria and their stress responses to ROS are important for the successful application of CP treatments. This review summarizes the sterilizing effects of exogenous ROS induced by plasma, bacterial oxidative stress protection and repair mechanisms, and regulation of their oxidative stress responses. The damaging effects of proven free radicals to bacterial cells are introduced. Stress protection and repair mechanisms of bacteria to exogenous ROS and their antioxidant properties including changes in bacterial cell morphology, biofilm protection in quorum sensing systems, as well as multiple antioxidant regulations in bacterial cells are also discussed. The recent studies conducted on the bacterial stress responses to ROS induced by CP treatments indicated that foodborne pathogens possess some resistance mechanisms to CP treatment in real food systems. Therefore, clarifying the development of resistance of foodborne pathogens to active substances produced by CP, balancing the relationship between minimum processing and food safety assurance, and translating laboratory results of the bacterial sterilization effectiveness of CP treatments into industrial applications should be focuses of future research.